Apparatus for measurement of textile flammability properties

ABSTRACT

A method and equipment for use in determining the rate of flame propagation and other burning characteristics of sheet materials wherein a test strip of material is supported adjacent its opposite edges and after being ignited is advanced toward the burning zone at a rate sufficient to maintain said zone in a predetermined location. The speed at which the strip of material is moved toward the burning zone is observed and recorded whereby the rate of flame propagation in the material under the test conditions can be determined. The equipment may be housed within an enclosure and the composition, pressure, humidity and other conditions of the atmosphere in which the burning of the material takes place can be varied and controlled so as to obtain consistent and accurate determinations as to the flammability and burning characteristics of the material under any predetermined conditions.

United States Patent Miller et a1.

1 June 6, 1972 [54] APPARATUS FOR MEASUREMENT OF TEXTILE FLAMMABILITYPROPERTIES [72] Inventors: Bernard Miller, Princeton; Harold Lambert,Pennington, both of N.J.; Charles H. Meiser, Jr., Yardley, Pa.

[73] Assignee: Textile Research Institute, Princeton, NJ.

[22] Filed: Jan. 13, 1971 [21] Appl. No; 106,115

Primary Examiner-Richard C. Queisser Assistant Examiner-HerbertGoldstein AttorneySperry and Zoda [57] ABSTRACT A method and equipmentfor use in determining the rate of flame propagation and other burningcharacteristics of sheet materials wherein a test strip of material issupported adjacent its opposite edges and after being ignited isadvanced toward the burning zone at a rate sufficient to maintain saidzone in a predetermined location. The speed at which the strip ofmaterial is moved toward the burning zone is observed and recordedwhereby the rate of flame propagation in the material under the testconditions can be determined.

The equipment may be housed within an enclosure and the composition,pressure, humidity and other conditions of the atmosphere in which theburning of the material takes place can be varied and controlled so asto obtain consistent and accurate determinations as to the flammabilityand burning characteristics of the material under any predeterminedconditions.

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RECORDER ATTORNEYS APPARATUS FOR MEASUREMENT OF TEXTILE FLAMMABILITYPROPERTIES FIELD OF INVENTION There has been a long continued and urgentdemand for the establishment of consistent and reliable tests orstandards by which the flammability and burning characteristics offabrics, films and other sheet materials can be determined. Typical ofthe problems presented and prior efforts to determine the fireresistance and rate of flame propagation in various sheet materials aredescribed in articles appearing in the Journal of the AmericanAssociation of Textile Chemists and Colorists at Vol. I, No. 12; (June4, 1969) and Vol. 2, No. 3 (Feb. ll, 1970). Despite the many attempts todevelop such tests and procedures, the equipment heretofore provided andthe results obtained in the use thereof have been so imprecise andinconsistent that it has not been possible to establish any generallyacceptable and meaningful standards for determining the rate of flamepropagation in textiles, films, papers and other types of sheetmaterial.

SUMMARY OF INVENTION In accordance with the present invention burningcharacteristics of sheet material are observed and evaluated bysupporting a strip of the material to be tested at its opposite edges ona drum which is rotatable about a horizontal axis. The strip is ignitedat a point near one end thereof and the drum is then rotated to advancethe strip toward the burning zone at a speed sufficient to maintain saidzone in a predetermined location. The location of the burning zone ofthe strip may be selected so as to cause the flame to extend eitherupward over an unburned portion of the strip, or upward away from anunburned portion of the strip or at a chosen angle with respect to thestrip. In any event the speed at which the drum must be rotated tomaintain the burning zone at the predetermined location and in theselected position with respect to the drum, will indicate the rate ofpropagation of flame in the material under the test conditions.

The equipment preferably is housed within an enclosure so that theconditions of the atmosphere in which the burning of the material takesplace can be controlled to maintain a desired oxygen content, pressure,humidity or the like.

The equipment may further be provided with means for protecting unburnedportions of the material from products of combustion or fusion which mayfall from the burning zone of the material. I

THE DRAWING FIG. 1 is a side elevation of a typical form of equipmentembodying the present invention; and

FIG. 2 is vertical sectional view of the equipment illustrated in FIG.I.

PREFERRED EMBODIMENT OF THE INVENTION In that form of the inventionchosen for purposes of illustration in the drawing the equipmentembodies a drum 2 mounted for rotation about a horizontal axis 4 andprovided with two horizontally spaced spoked wheels or members 6 and 8through which air and gases may circulate freely. The wheels 6 and 8have radially extending pins 10 projecting from the periphery thereof toengage the edges of a strip of material 12 to be tested. The strip maybe held in engagement with the pins 10 by suitable means such as theflexible retaining bands 14 which extend about the periphery of thewheel and overlie the edges of the strip. The opposite ends of theretaining bands 14 are turned inwardly so as to enter and engage theopposition sides of a retaining notch 16 or the like on the periphery ofthe wheel. The retaining bands 14 thus hold the strip of material inengagement with the pins 10 and in a position wherein the strip 12extends transversely of the drum with the central portion of the stripunsupported. The size of the drum may be chosen as desired but in atypical construction the wheels 6 and 8 are 8 inches in diameter andspaced at least 1% inches apart. However, the spacing between the wheelsis preferably adjustable to receive strips of any desired width. Thestrip of material used in carrying out any test may then be from 20 to25 inches in length and at least 2 inches in width. When thusdimensioned the duration of the burning and testing operation willgenerally be long enough to assure stabilization of the flame andaccurate observation thereof. At the same time the spacing of the wheels6 and 8 is such that they will not influence or interfere with thepropagation of flame in the test material by the removal of heat,confining of the flame, or interference with the circulation of gasesinto and out of contact with the material. I

The material to be tested may be ignited by any suitable means such as agas flame projected downwardly from a jet 18 located at a point near thetop of the drum 2 and mid-way between the spaced wheels 6 and 8. Theflame may be produced and controlled by any suitable means (not shown).

The drum 2 with the strip of material 12 mounted on the peripherythereof may be rotated by any preferred driving mechanism, such as avariable speed motor 20, speed reducer 22, shaft 24 and bevelled gears26; The speed of rotation of the drum 2 and the rate of linear travel ofthe material 12 under test are preferably recorded by a tachometer 28 orthe like, while the speed of rotation of the drum may be varied asdesired by a control device 30.

For most purposes the equipment is housed within an enclosure 32 towhich gases, such as a mixture of nitrogen and oxygen, are admittedunder control of a pressure regulating valve 34. A gas distributing head36 and a body of glass beads 38 or the like in the lower portion of theenclosure, serve to assure uniform flow of the gases upward through theenclosure 32 to a vent or outlet 40. If desired a unit 42, such as acalorimeter, gas analyzer, smoke detector or the like may be arranged toreceive the gases and products of combustion issuing from the outlet 40.Further, if desired pressure relief means may be incorporated in theunit 42 or elsewhere to permit the atmosphere within the enclosure 32 tobe maintained above or below atmospheric pressure or to establish adesired humidity, temperature or other condition in the atmosphere inwhich the material under test is to be burned.

The enclosure 32 may be formed of glass or other transparent material ormay be provided with a sight glass permitting observation of thematerial under test. If preferred, or in addition to any sight glassprovided, a thermocouple or radiation sensing device 44 may bepositioned to be actuated by the flame produced by the burning of thematerial under test. Such a sensing device may be located at anysuitable or preferred point about the periphery of the drum 2 and two ormore sensors may be provided and positioned at selected points withrespect to the test material if desired.

In operating the equipment described, the strip of material 12 to betested is applied to the wheels 6 and 8 of the drum 2 and held in placeon the periphery of the drum by the clamping members 14. One end of thestrip is preferably located near the retaining notch 16 in the l loclock" position near the top of the drum and beneath the gas jet orother ignition device 18. The gas jet is ignited and used to initiateburning of the strip 12 near the leading end thereof and then is removedwhile the motor 20 is energized to rotate the drum 2 with the testmaterial thereon, say in a clockwise direction as seen in FIG. 1. Thedrum is rotated at whatever rate necessary to move the flame quickly tothe predetermined test position.

When the test point chosen is in the 3 o'clock" position of FIG. 1, forexample, the flame from the burning material will extend upward from theburning zone about or over the unburned material surrounding the upperportion of the drum. The motor control device 30 is then actuated toadjust the clockwise speed of rotation of the drum and test material soas to maintain the burning zone of material at the 3 oclock" locationand this speed can be maintained as the drum continues to rotate anduntil the end of the test strip is reached. Adjustment in the speed ofrotation of the drum may be controlled manually if desired. However, bylocating the thermocouple 44 or other flame sensing means above the "3o'clock" position or in some other suitable position to respond to thepresence of a flame in the 3 oclock" position the speed of rotation ofthe driving motor 20 may be automatically confound to be aboutrevolution per minute-allowing nearly 2 minutes for observation of theburning strip being evaluated. Such prolonged and detailed study andobservation of the burning characteristics of materials has not beenpossible heretofore and renders it possible to attain the high degree ofaccuracy and consistency in test results to establish uniform standardsas to the flammability of materials.

While the operation of the equipment as described above presumes thatthebuming zone will be maintained in the 3 o'clock" position wherein theflame from the burning material extends upward over the advancingunburned portion of the test strip, it is also of practical interest toconduct tests and evaluation of materials when the burning zone is at 12oclock, 9 oclock, or any location in between. For some purposes and fora complete evaluation of the burning characteristics of materials it maybe desirable to run successive tests on strips of the same material withthe burning zone held in several different positions about the drum.

The equipment of the present invention may be used in determining theburning characteristics of practically any type of sheet materialincluding textile materials formed from any of the naturally'occurringand man-made fibers such as cotton, wool, silk, nylon, polyester and thelike, as well as mixtures or blends of such fibers. Plastic films,paper, felts, floor coverings, rubber sheeting, and laminated materialsas well as the properties of metal foils, screen, and wall board orflexible plywood may be evaluated in the same way by means of thepresent invention.

In testing sheet material formed of fibers or plastic compositions whichmay fuse or melt or develop sparks or charred products which tend todrip or fall from the burning zone onto unburned portions of thematerial on the lower part of the drum, it is generally desirable toprovide the drum with a wire mesh screen or-the like which is locatedwithin the drum as shown at 50. Such a screen or shield should be spacedfrom the periphery of the drum and the test material a sufficientdistance to avoid any interference or adverse influence on the burningcharacteristics of the material and the free flow of gases into and outof contact therewith.

in order to obtain a more extended evaluation of the bumingcharacteristics of materials, the gases introduced into the enclosure tomaintain the desired atmosphere adjacent the material being tested maybe varied in composition, pressure and other properties. For mostpurposes it is desired to introduce a mixture of nitrogen and oxygeninto the enclosure 32. The percent of oxygen can be varied over anextended range and it has been found in general that there is a linearrelationship between the burning rate and the volume fraction of theoxygen. The slope of the relationship representing the sensitivity ofthe burning rate to oxygen appears to increase as the fabric weightdecreases. Other significant relationships can also be determined, asfor example, the fact that fabrics containing a mixture of fibers suchas 50/50 polyester and cotton, exhibit quite different burningcharacteristics when the cotton yarns extend in the direction of theflame rather than transverse to the flame-the latter being substantiallyless sensitiveto the oxygen content of the atmosphere in which bumingtakes place.

in a like manner the pressure of the atmosphere in which the tests arecarried out may be at, above, or below atmospheric pressure. Thehumidity may be controlled or varied and other properties of theatmosphere within the enclosure 32 may be selected to obtain an extendedand varied series of data on the burning properties of sheet material.Moreover, analysis of the products of combustion and determinations withrespect to the heat developed in burning materials under varyingconditions can be obtained in the practice of the present invention. Itshould therefore be understood that the particular construction andmethods of utilizing the .equipment of the present invention as shown inthe drawing and described above, are intended to be illustrative onlyand are not intended to limit the scope of the invention.

We claim:

1. Equipment for determining a burning characteristic of sheet materialcomprising a rotatable drum, means for supporting the sheet material tobe evaluated on the periphery of said drum, means for igniting saidsheet material, means for rotating said drum with the ignited materialthereon about a horizontal axis, means for varying the speed of rotationof said drum to maintain the ignited portion of the sheet material in apredetermined location, and means for determining the speed of rotationof said drum.

2. Equipment as defined in claim 1 wherein said drum includes parallelmembers between which the material to be evaluated is suspended.

3. Equipment as defined in claim 1 wherein said drum and material areenclosed within a housing and means are provided for controlling theatmosphere within the housing.

4. Equipment as defined in claim 3 wherein said drum and material areenclosed within a housing and means are provided for controlling theoxygen content of the atmosphere within the housing.

5. Equipment as defined in claim 3 wherein said drum and material areenclosed within a housing and means for controlling the pressure of theatmosphere within the housing.

6. Equipment as defined in claim 1 wherein temperature sensing means arepositioned to respond to the temperature of flame produced on burning ofthe material.

7. Equipment as defined in claim 1 wherein a thermocouple is positionedadjacent said predetermined location.

8. Equipment as defined in claim 1 wherein the means for determining thespeed of rotation of said drum includes a recording device.

9. Equipment as defined in claim 1 wherein means are provided forprotecting the material being evaluated from the ignited material andproducts resulting from ignition thereof.

10. Equipment as defined in claim 1 wherein a screen is mounted withinthe drum and positioned to catch molten material and products fallingfrom the ignited sheet material.

11. Equipment as defined in claim 1 wherein said drum embodies twosimilar spaced parallel members having circular peripheral edges andmeans on said edges for holding sheet material in a position extendingtransversely between said members.

12. Equipment for determining a burningcharacteristic of sheet materialcomprising two horizontally spaced supports engagable with oppositeedges of a sheet of material to be evaluated, means located adjacentsaid sheet for initiating burning of said sheet material, means formaintaining a burning zone of said sheet material in a predeterminedlocation in eluding means for advancing an unignited portion of saidmaterial toward said burning zone so as to maintain the buming zone ofthe material in said location, and means for determining the rate atwhich said material is advanced toward said location.

13. The method of determining a burning characteristic of sheet materialwhich comprises the steps of holding an elongated strip of the materialsuspended between parallel supports, initiating burning of said strip ata point spaced from one end of the strip, moving the strip toward theportion of the strip which is burning at a speed which will serve tokeep the content of the atmosphere within said enclosure is maintainedsubstantially constant.

17. The method as defined in claim 15 wherein the pressure of theatmosphere within said enclosure is maintained substantially constant ata value above atmospheric pressure.

18. The method as defined in claim 15 wherein the position of theunburned portion of said strip of material with respect to the burningportion of the material is maintained substantially constant.

1. Equipment for determining a burning characteristic of sheet materialcomprising a rotatable drum, means for supporting the sheet material tobe evaluated on the periphery of said drum, means for igniting saidsheet material, means for rotating said drum with the ignited materialthereon about a horizontal axis, means for varying the speed of rotationof said drum to maintain the ignited portion of the sheet material in apredetermined location, and means for determining the speed of rotationof said drum.
 2. Equipment as defined in claim 1 wherein said drumincludes parallel members between which the material to be evaluated issuspended.
 3. Equipment as defined in claim 1 wherein said drum andmaterial are enclosed within a housing and means are provided forcontrolling the atmosphere within the housing.
 4. Equipment as definedin claim 3 wherein said drum and material are enclosed within a housingand means are provided for controlling the oxygen content of theatmosphere within the housing.
 5. Equipment as defined in claim 3wherein said drum and material are enclosed within a housing and meansfor contrOlling the pressure of the atmosphere within the housing. 6.Equipment as defined in claim 1 wherein temperature sensing means arepositioned to respond to the temperature of flame produced on burning ofthe material.
 7. Equipment as defined in claim 1 wherein a thermocoupleis positioned adjacent said predetermined location.
 8. Equipment asdefined in claim 1 wherein the means for determining the speed ofrotation of said drum includes a recording device.
 9. Equipment asdefined in claim 1 wherein means are provided for protecting thematerial being evaluated from the ignited material and productsresulting from ignition thereof.
 10. Equipment as defined in claim 1wherein a screen is mounted within the drum and positioned to catchmolten material and products falling from the ignited sheet material.11. Equipment as defined in claim 1 wherein said drum embodies twosimilar spaced parallel members having circular peripheral edges andmeans on said edges for holding sheet material in a position extendingtransversely between said members.
 12. Equipment for determining aburning characteristic of sheet material comprising two horizontallyspaced supports engagable with opposite edges of a sheet of material tobe evaluated, means located adjacent said sheet for initiating burningof said sheet material, means for maintaining a burning zone of saidsheet material in a predetermined location including means for advancingan unignited portion of said material toward said burning zone so as tomaintain the burning zone of the material in said location, and meansfor determining the rate at which said material is advanced toward saidlocation.
 13. The method of determining a burning characteristic ofsheet material which comprises the steps of holding an elongated stripof the material suspended between parallel supports, initiating burningof said strip at a point spaced from one end of the strip, moving thestrip toward the portion of the strip which is burning at a speed whichwill serve to keep the burning portion of said strip in a predeterminedlocation, and determining the speed at which said strip is moved towardthe burning portion thereof.
 14. The method as defined in claim 13wherein the supports for said material are rotated about a horizontalaxis while the material is burning.
 15. The method as defined in claim13 wherein the material and its supports are located within an enclosureand a condition of the atmosphere within said enclosure is maintainedsubstantially constant while said material is burning.
 16. The method asdefined in claim 15 wherein the oxygen content of the atmosphere withinsaid enclosure is maintained substantially constant.
 17. The method asdefined in claim 15 wherein the pressure of the atmosphere within saidenclosure is maintained substantially constant at a value aboveatmospheric pressure.
 18. The method as defined in claim 15 wherein theposition of the unburned portion of said strip of material with respectto the burning portion of the material is maintained substantiallyconstant.